Rewritable optical discs have had a maximum storage capacity of approximately 650 MB, but this limit has been pushed to several gigabytes by the introduction of DVD-RAM discs, a phase-change type of storage medium. Used in conjunction with practical implementations of MPEG (particularly MPEG-2), a digital AV data encoding standard, DVD-RAM is not limited to computer applications and will soon find widespread use as a recording and playback medium in the audio-video (AV) and even home entertainment industries.
With the start of digital broadcasts in recent Japan, it has become possible to multiplex and simultaneously transmit the video, audio, and data portions of plural programs to the MPEG transport stream (“MPEG-TS”). Digital broadcast recorders using hard discs or DVD media to record these programs are also available. As a standard for such an information recording medium in the next generation, which is suitable for recording digital broadcasting, there is Blu-ray Disc standard (“BD standard”).
The next generation digital broadcast recorder (Blu-ray Disc recorder) does not convert broadcasted MPEG-TS but records mainly data in MPEG-TS format according to a format of digital broadcasting. The next generation digital broadcast recorder records AV stream in MPEG-TS format even when self-recording AV data received from external. This is because it becomes unnecessary for the recorder to handle both MPEG program stream (“MPEG-PS”) and MPEG transport stream.
However, because the current DVD standards (including the DVD-Video standard, DVD-Audio standard, DVD Video Recording standard, and DVD Stream Recording standard) use the MPEG-PS for recording AV stream, MPEG-TS to MPEG-PS conversion (“TS2PS conversion”) is required in order to convert content recorded in the MPEG-TS format, such as by the above-noted next generation digital broadcast recorder, to the DVD-Video format, for example.
Converting a stream multiplexed to the MPEG-TS to MPEG-PS, however, involves a complex recalculation for decoder buffer management, the TS2PS conversion is time-consuming, and often involves re-encoding the elementary stream, resulting in degraded image quality and sound quality.
Against these problems, some solving methods are proposed (see patent document 1, for example).
*** Patent document 1: JP-A-2003-228922